Ribbon feed mechanism of typewriters



This invention relates to improvements in the ribbon feed mechanism oftypewriters and its object is to provide a ribbon feed which is simple and cheap to produce and which is easily assembled;

According to this invention a cam driven from the carriage escapement wheel reciprocates two links having detents thereon movable into and out of operative positions and adapted when in their operative positions to turn step by step a ratchet wheel secured on the axles of the respective ribbon spools of the machine. Cams are provided in association with the detents and the cams are adjusted to move the detents into or out of their operative positions and the cams are interconnected and arranged so that when one detent is in its operative position the other detent is in its inoperative position and vice versa and the ratchet wheels on the ribbon spool axles are arranged so that when the respective detents are in their operative positions they actuate the ratchet wheels to turn the ribbon spools to take up the ribbon so that by adjusting the positions of the detent control cams the direction of feed of the ribbon can be reversed.

The invention will now be more particularly described with reference to the accompanying drawings in which:

FIG. 1 is a sectional elevation, and

FIG. 2 a plan of ribbon feed mechanism for a typewriter constructed according to this invention.

FIG. 3 is an enlarged plan showing the ratchet wheel and detent mechanism for driving one of the ribbon spool axles, the other ribbon spool axle being driven in a similar manner.

FIG. 4 is a plan of the cam which reciprocates the links which carry the detents for operating the ratchet wheels on the ribbon spool axles.

Like numerals indicate like parts throughout the drawings.

In carrying out this invention an axle 1 driven from the carriage escapement wheel 2 or being an extension of the axle of the escapement wheel is disposed vertically in the machine. On the lower end of this vertical axle 1 is mounted a cam 3 which may be secured to the vertical axle 1 or is preferably driven from the axle by a free wheel clutch 4 as shown in FIG. 1 as the carriage of the machine traverses from right to left during typing. The lower end of the vertical axle 1 passes through slots 5, 6 in two links 7, 8 which extend respectively from the vertical axle 1 to the axles 9, 10 of the ribbon spools 11, 12. The links 7, 8 may be formed from strips of metal of suitable width and thickness and strengthened v by forming ribs therein. The links 7, 8 are disposed at an angle of approximately ninety degrees relatively to each other and the cam 3 on the vertical axle 1 is disposed between two abutments 15, 16 on the link 7 and 17, 18 on the link 8 so that as the vertical shaft 1 and cam 3 rotates reciprocating motion is transmitted to the links 7, 8. The abutments 15, 16 and 17, 18 may be formed in the respective links when the latter are formed from strip material by suitably bending the strip as shown in the drawings.

Downward extensions of the spool axles 9, 10 pass respectively through slots 19, 20 in the ends of the respective links 7, 8 to allow for the reciprocating motion of the latter. In order to transmit the reciprocating motion of the links 7, 8 to the spool axles 9, 10 to turn the latter, the following arrangement is adopted. Secured on r Egg the lower end of each spool axle is a ratchet wheel 21 and on the end of each of the links 7, 8 is a detent 22 to engage with each ratchet wheel 21 and turn the ratchet wheels step by step as the links reciprocate. Each detent 22' is conveniently made from spring steel wire and is substantially U shaped as shown more clearly in FIG. 3. The inner ends of the side arms of the detents engage in slots 23 in the sides of each link 7, 8 to hold them in position thereon and the outer ends'of the side arms of the detents are bent at right angles to the remainder of the arms to provide parts 24 on the detents to engage with the teeth of the respective ratchet wheels 21. Normally the said parts 24 engage with the teeth of the ratchet wheels 21 by reason of the U shaped formation of the detent 22.

It will be understood that only one detent is in operation at any time and in order to provide for this and to enable a change to be made from one detent to the other to reverse the ribbon feed, a cam 25 is provided on each of the spool axles 9, 10. These cams 25 are disposed between the parts 24 of the detent 22 which engage with the teeth of the ratchet wheels 21 and in one position of the cams 25 as shown in full lines in FIG. 3, the said parts 24 engage with the teeth of the ratchet wheel and in a second position as shown in broken lines in FIG. 3 the cams 25 engage with the said parts 24 and move them clear of the teeth. In order to turn the cams 25 from one position to the other each cam 25 has an arm 26 thereon. The two arms 26 are connected together by a link 27 so that both cams 25 move at the same time and one arm 26 is connected to a manually operated lever 28 readily accessible to the machine operator. The cams 25 are arranged so that when one detent 22 is in operation, the other detent is held by its cam in an in operative position and vice-versa and the positions of the cams are changed to reverse the direction of the ribbon feed by moving the manually adjustable lever 28. .A change in the direction of the ribbon feed is necessary when the ribbon is nearly unwound from either spool and a visible indication of this is provided by the provision of a staple or clip at an appropriate point in the ribbon.

The cam 3 on the axle 1 is preferably driven by a free wheel clutch 4 and for this purpose the cam 3 is loosely mounted on the axle 1 and is provided with teeth 29 thereon (see FIG. 4) which engage with teeth on a member 30 secured on the axle 1, the teeth on the cam 3 being normally held in engagement with the teeth on the member 30 by a spring disc 31 secured on the axle 1. The teeth 29 are arranged so that the cam 3 is only driven when the carriage of the machine is moving from right to left which is the normal direction of movement when the keys of the machine are operated so that the ribbon feed does not operate on the return motion of the carriage.

A ribbon feed constructed as described is simple and cheap to produce and is easily assembled and it has the advantage that it is not operated by the key levers of the machine, thus providing for easier operation of the latter.

What I claim is:

1.- Ribbon feed mechanism for a typewriter comprising an axle driven from the carriage escapement wheel, a cam thereon, two ribbon spools, a ribbon carried thereby, axles to carry the ribbon spools, links extending from the axle driven by the carriage escapement wheel to the respective ribbon spool axles, two abutments on each link for engagement by the cam, a ratchet wheel on each ribbon spool axle, a detent on each link to engage with the teeth of the ratchet wheels, and means to hold'each detent in an inoperative position, said means being interconnected so 3 that when one detent is in its operative position the other detent is held in its inoperative position.

2. Ribbon feed mechanism according to claim 1 in which the cam is driven from the axle driven from the carriage escapement wheel by means of a free wheel clutch;

3. Ribbon feed mechanism'according to claim 1 in which the detents on the links are substantially U shaped and the outer ends of the side arms of the detents are bent at right angles to the remainder of the arms to provide parts to engage the teeth of the ratchet Wheels on the ribbon spool axles.

4. Ribbon feed mechanism according to claim 3 in which the side arms of the U shaped detents engage in slots in the sides of: the links.

A; 5. Ribbon feed mechanism according to claim 3 in which the means to hold each detent in an inoperative References Cited in the file of this patent UNITED STATES PATENTS 884,691 Volker 1 Apr. 14, 190 991,154 Kavle May 2, 1911 1,338,699

Roberts May 4, 1920 

